i only glanced through this, but it looks like the main couple are the two tour guides (?). However, the girlfriend used to be in a relationship with one of the older guys in their tour group -- I believe she was i an affair with him, as the old guy says he was married. She falls for him again and cheats on her boyfriend. The boyfriend catches her in the act later on, even seeing her agree to raw sex and being ejaculated inside of. The next morning she interacts with him as if nothing happens.
After the tour ends, the boyfriend breaks up with her over the phone without telling her that he knows she cheated. He says it was a shock to her and she kept crying on the phone, asking him why. He moved on to a different company and didn't really see her again. Months later, he heard that his now ex-girlfriend is pregnant and married to the old guy. The boyfriend has no animosity towards her, silently wishes her the best, and thanks her for the memories. No huge loss, though, as she seemed to be fucking other people anyway.
I love that this author has protagonists that do their best to move on, instead of the usual dudes who are weak and broken down. I also love that he writes multiple viewpoints. We get the protagonists POV, the woman's POV, and sometimes even the netoriya's POV. That said, it's funny how all of the women in his stories are trash, though.
Thank you for the run down. And yeah the females in his series are not at all faithful.
According to http://www.dlsite.com/ecchi-eng/work/=/product_id/RE145713.html
* Characters
Takashi - protagonist / a tour guide Iroha - Takashi's girlfriend / works at the same travel agency Mr. Watanabe - Iroha's manager / recently married Mr. Tanaka - a client of the travel agency
* Story
Takashi was a tour guide for a company where he'd now been dating Iroha, his coworker and coordinator, for three years. Perhaps because of her position her demeanor was a bit cold.
During a catered banquet of a tour, Iroha was accosted by Mr. Tanaka, one of their most important clients. He was persistent. Iroha was concerned about who was watching. But she could not deny the excitement. With moist loins she went with him to another room...
Meanwhile, Takashi was called on to break up another indecency. It seemed a man from the company had hooked up with a call girl. Rather than stop it, he watched them.
Some time later...
Company manager Watanabe met with Iroha privately to thank her. She felt particularly distant from her Takashi, and when her boss kissed her and caressed her, her thoughts turned to opportunity... Takashi needn't know about this. In the end Iroha yearned for the heat of a man, and accepted Watanabe's.
But Takashi had also been called to meet Watanabe. From the next room he could hear everything. Iroha was passionate with another man in ways she'd never been with him.
So many wrongs were happening on this tour. Takashi couldn't collapse in emotion or confront anyone. All he could do, is pretend he knew nothing.